Bacterial infections have long been treated with effective agents such as quinolones, penicillins, and cephalosporins. However, a growing number of bacteria are becoming resistant to conventional agents, and accordingly, new drugs are needed to treat resistant strains.
Unlike bacterial infections, viral diseases have not had a wide range of agents available for treatments. While many viral infections have afflicted mankind for many years, certain diseases have only recently attracted attention due to severity and limited treatments available. Of particular importance is the viral infection known as acquired immune deficiency syndrome (AIDS).
AIDS is a very serious disease worldwide. AIDS infections have increased dramatically within the past several years. Estimates of reported cases in the very near future also continue to rise dramatically. Consequently, there is a great effort to develop drugs and vaccines to combat AIDS.
The AIDS virus was first identified in 1983. It has been known by several names and acronyms. It is the third known T-lymphocyte virus (HTLV-III), and it has the capacity to replicate within cells of the immune system, causing profound cell destruction. The AIDS virus is a retrovirus, a virus that uses reverse transcriptase during replication. This particular retrovirus is also known as lymphadenopathy-associated virus (LAV), AIDS-related virus (ARV) and, most recently, as human immunodeficiency virus (HIV). Two distinct types of HIV have been described to date, namely HIV-1 and HIV-2. The acronym HIV will be used herein to refer to HIV viruses generically.
HIV is known to exert a profound cytopathic effect on the CD4+ helper/inducer T-cells, thereby severely compromising the immune system. HIV infection also results in neurological deterioration and, ultimately in the death of the infected individual.
The field of viral chemotherapeutics has developed in response to the need for agents effective against retroviruses, in particular HIV. There are many ways in which an agent can exhibit antiretroviral activity. For example, HIV requires at least five viral proteins for replication: reverse transcriptase (RT), protease (PR), transactivator protein (TAT), integrase (IN), and regulator of virion-protein expression (REV). In addition, there are several structural proteins that play an important role in the replication and cell to cell transfer of HIV. These include the CD4 binding protein GP120, the nucleocapsid protein NCp7, and the fusion protein GP41. Accordingly, viral replication could theoretically be inhibited through binding or inhibiting any one or all of the proteins involved in the viral replication cycle.
A large number of antiretroviral agents, such as AZT, ddC, TIBO, and the like are known to inhibit RT. There also exist antiviral agents that inhibit transactivation by inhibiting the function of the protein TAT.
A useful approach being investigated recently for potential use in the treatment of AIDS is the development of synthetic peptides as inhibitors of the retroviral protease. It is known that retroviruses, including HIV, express their genetic content by directing the synthesis of a polyprotein by the host. The polyprotein is a precursor molecule, which is processed through proteolysis to generate essential viral enzymes and structural proteins. The virally encoded protease is contained within the polyprotein and is responsible for cleaving the polylprotein to yield mature viral proteins. Since the protease is known to be required for viral replication, it has been a therapeutic target for the development of AIDS drugs. These efforts have generated over 50 potent inhibitors of the protease. Several of these inhibitors are scheduled for clinical trials.
Other major efforts are underway to inhibit viral entry into target cells by identifying chemical entities that block the viral receptor. The viral fusion protein has recently been targeted for this approach. In addition, the nucleocapsid protein NCp7 has been recognized as an essential viral protein and its inhibition has been reported.
An object of this invention is to provide a new series of organic molecules which have been found to exhibit excellent antiviral activity in tests recognized to be predictive of agents useful to combat AIDS. A further object of the invention is to provide compounds having antibacterial activity. The invention additionally provides pharmaceutical compositions which are useful in treating viral and bacterial infections, and also provides a therapeutic method for treating such infections.